A method for coupling swmm and lisflood-fp objectification considering element space form

Abstract

The application discloses a SWMM and LISFLOOD-FP object-oriented coupling method considering element space forms, first determines SWMM and LISFLOOD-FP element objects to be coupled, including point, point set and surface element objects; then based on element semantic information, different generalization forms of geographical elements in the model are established, and unified space matching rules between SWMM and LISFLOOD-FP models are established; finally, in the consistent time process, the space matching results of different element objects are used for flow exchange and flow distribution. The application supports expression and coupling of point, surface and point set element objects, and establishes element space matching rules based on element semantic information. The application supports unified space expression and flow exchange of element objects according to different form characteristics of elements, and can more accurately describe water accumulation distribution and flow exchange conditions of surface drainage facilities.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of urban rain flood simulation and geographic information system, and particularly relates to a SWMM and LISFLOOD-FP object-oriented coupling method considering the spatial form of elements. BACKGROUND

[0002] Urban rain flood is the general term of runoff in urbanized areas, pipe network confluence and river flood process, is an important means to simulate urban waterlogging, in the past few decades, many urban rain flood simulation software has appeared to express the urban rain flood process, but the existing single model cannot fully represent all the details of the modeling system, therefore, multi-model coupling for hydrological comprehensive modeling to solve complex hydrological problems has become a research hotspot.

[0003] SWMM (storm water management model) is a software developed by the University of Florida, USA, mainly applied to urban area hydrology and water conservancy simulation, which is a rainfall-runoff model, which can simulate the hydraulic state of river and pipe network, but cannot reflect the surface runoff process, and uses a vectorization method to express pipe points, water storage tanks, drainage buildings and other geographic elements.

[0004] LISFLOOD-FP is a two-dimensional hydrodynamic model developed by the University of Bristol, UK, which is a distributed hydrological model, compared with SWMM, it has a clear surface runoff process, and can reflect the distribution of water on the ground. LISFLOOD-FP describes elements based on grid, all elements exist in the form of grid in LISFLOOD-FP.

[0005] For the expression of geographic elements such as pipe points, water storage tanks and drainage buildings, SWMM generalizes them into vector point elements, while for LISFLOOD-FP, these elements exist in the form of grid points on the terrain of the study area, and occupy different numbers and positions of grid according to the form characteristics of the elements. Unfortunately, the current mainstream coupling method of SWMM and LISFLOOD-FP does not take into account the spatial expression difference of vector and grid elements, generalizes the elements in LISFLOOD-FP into points with the same or similar position as the elements in SWMM, and simply generalizes the coupling process as point-point coupling.

[0006] In specific application scenarios, the coupling scheme between SWMM and LISFLOOD-FP is heterogeneous, and the technology selection, data processing and coupling architecture are different to different degrees. However, looking at the existing methods, the spatial coupling method of SWMM and LISFLOOD-FP does not consider the morphological characteristics of the elements. For the sake of simulation speed and efficiency, the existing methods simply generalize the drainage elements such as drainage buildings and pipe points into point elements, for example, the paper "Urban Rainstorm Waterlogging Simulation Based on SWMM and LISFLOOD-FP Model: A Case Study of Jinan City" (Li Peng, Xu Zongxue, Zhao Gang, Zuo Binbin, Wang Jingjing, Song Sulin. South-to-North Water Diversion and Water Conservancy Technology (English), 2021, 19(06)) ignores the spatial form characteristics of drainage elements, and is a point-point coupling method; the paper "Rainstorm Waterlogging Simulation Based on SWMM and LISFLOOD Model" (Zeng Zhaoyang, Wang Zhaoli, Wu Xushu, Lai Chengguang, Chen Xiaohong. Journal of Hydroelectric Engineering, 2017, 36(05): 68-77.) points out that the bci file in LISFLOOD stores overflow node coordinates, without considering the morphological characteristics of large-scale drainage facilities in cities, which is a point-point coupling method; the Chinese patent entitled "A High-precision Urban Rainstorm Simulation Method Based on GPU Acceleration Coupling Pipe Network" establishes the matching relationship between nodes and grids based on the nearest principle, which is still a point-point coupling spatial coupling method; the Chinese patent entitled "A Surface Water Rapid Simulation Method and System Based on Vertical Boundary Coupling" uses a point-point coupling spatial coupling method when constructing the topological connection relationship between inspection wells, drainage pipes and two-dimensional grids; these methods do not consider the shape, size and other spatial morphological characteristics of elements on the grid. SUMMARY

[0007] The purpose of the present application is to provide a SWMM and LISFLOOD-FP object-oriented coupling method considering the spatial form of elements in the process of urban rainstorm spatial coupling simulation.

[0008] Technical scheme: The present application aims to provide a SWMM and LISFLOOD-FP object-oriented coupling method considering the spatial form of elements, which specifically comprises the following steps:

[0009] (1) Determine the elements to be coupled in SWMM and LISFLOOD-FP; the element object is expressed in the form of a node in SWMM and has a unique identifier to identify the element, and exists in the form of a grid multi-point in LISFLOOD-FP;

[0010] (2) Based on the semantic information of the elements, a unified spatial matching rule between SWMM and LISFLOOD-FP models is established for different generalized forms of geographical elements in the models;

[0011] (3) Flow exchange and distribution between SWMM and LISFLOOD-FP: In the consistent time process, the flow exchange and distribution are carried out between the same elements according to the spatial matching rules established in step 2.

[0012] Further, the coupling elements in step (1) include point objects, surface objects, and point set objects; when the shape and size of the elements are smaller than the spatial resolution of the grid, the grid range is a point; when the shape and size of the elements are larger than the spatial resolution of the grid, if the spatial distribution of the pipe network inside the building is not considered, the grid range is a surface, otherwise, the grid range of the elements is a point set.

[0013] Further, the step (2) is implemented as follows:

[0014] (21) Construction of the spatial range mapping of the elements to determine the boundaries of the geographic element vector and the grid;

[0015] (22) Construction of the element semantic mapping relationship between SWMM and LISFLOOD-FP; the boundary condition of QVAR is used in LISFLOOD-FP, and the boundary condition name of any grid point in the grid range corresponding to the element in LISFLOOD-FP is the same as the unique identifier in SWMM;

[0016] (23) Establishment of the element flow exchange channel between SWMM and LISFLOOD-FP: A synchronous flow exchange channel is provided for SWMM and LISFLOOD-FP, which stores the flow rate information of the elements to carry out flow exchange and distribution.

[0017] Further, the step (3) is implemented as follows:

[0018] When the element node overflows, the overflow flow is redistributed on the surface grid corresponding to the element using the flow exchange channel, and the flow value of the time series of the boundary condition on each corresponding grid of LISFLOOD-FP is:

[0019] q = Q / n

[0020] Where Q is the node overflow flow in SWMM, n is the number of grid points corresponding to the element node, and q is the time series flow rate value of the node;

[0021] When the element node does not overflow, the element flow in LISFLOOD-FP enters the SWMM pipe network through the flow exchange channel, the flow in the element range in LISFLOOD-FP is included in the calculation, and the corresponding flow value is subtracted from each grid corresponding to the element in LISFLOOD-FP, and the weighted average of the water on the surface grid corresponding to the element is added to the pipe network:

[0022]

[0023] Wherein, the total inflow of the element of SWMM is Q, the outflow of each grid corresponding to the element in LISFLOOD-FP is q, n is the number of grid points corresponding to the element node, C is an empirical parameter, A is the area of the inspection well, and h is the water depth of the point.

[0024] Further, the step (21) is implemented as follows:

[0025] The vector space position of the geographic element is the absolute coordinate of the geographic element, for the grid boundary, if the grid element type is a point, the grid boundary is the corresponding position grid row and column number, if the grid element type is a surface, the grid boundary is the grid range row and column number of the corresponding element surface, and if the grid element type is a point set, the grid boundary is the accurate space position row and column number of the corresponding element internal pipe point.

[0026] Beneficial effects: compared with the prior art, the beneficial effects of the present application are as follows: the present application supports the expression and coupling of point, surface and point set element objects, and establishes element space matching rules based on element semantic information, supports unified space expression and flow exchange of element objects according to different morphological characteristics of elements, and can more accurately describe the water accumulation distribution and flow exchange of surface drainage facilities. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is a flowchart of the method of the present application;

[0028] Figure 2 is an example of the establishment of SWMM elements and identifiers thereof;

[0029] Figure 3 is an example of the establishment of LISFLOOD-FP elements and identifiers thereof;

[0030] Figure 4 is a schematic diagram of the spatial coupling mode supported by the present application;

[0031] Figure 5 is a schematic diagram of the result of urban rain flood process simulation by using the spatial matching method of the present application. DETAILED DESCRIPTION

[0032] The present application will be further described in detail below with reference to the accompanying drawings.

[0033] Figure 1 is a flowchart of the method of the present application. The method comprises the following steps:

[0034] Firstly, the spatial position of the matching element is determined, including determining the node of the element to be coupled in SWMM and giving it a unique identifier, and determining the row and column number of the element in LISFLOOD-FP.

[0035] The element to be coupled in SWMM and LISFLOOD-FP is determined; the element object is expressed in the form of a node in SWMM and has a unique identifier to identify the element, and exists in the form of a grid multi-point in LISFLOOD-FP. Coupling elements include point objects, surface objects, and point set objects; when the shape and size of the element are smaller than the spatial resolution of the grid, the grid range is a point; when the shape and size of the element are larger than the spatial resolution of the grid, if the spatial distribution of the pipe network inside the building is not considered, the grid range is a surface, otherwise, the grid range of the element is a point set.

[0036] Secondly, the spatial matching rule is established, and the correspondence relationship of the same element between SWMM and LISFLOOD-FP is determined based on the semantic information of the element object. Then, time matching is performed; SWMM and LISFLOOD-FP reach the same simulation time, and the flow exchange and distribution are performed.

[0037] The spatial matching rule of the coupled element object is unified, and the matching relationship of the element between SWMM and LISFLOOD-FP is determined based on the semantic characteristics of the element: firstly, the spatial range mapping relationship of the element is constructed to determine the vector and grid boundary of the geographic element; the vector spatial position of the geographic element is the absolute coordinate of the geographic element, for the grid boundary, if the grid element type is a point, the grid boundary is the corresponding position grid row and column number, if the grid element type is a surface, the grid boundary is the grid range row and column number of the corresponding element surface, and if the grid element type is a point set, the grid boundary is the accurate spatial position row and column number of the corresponding internal pipe point of the element; secondly, the semantic mapping relationship of the geographic element in SWMM and LISFLOOD-FP is constructed; QVAR boundary conditions are used in LISFLOOD-FP, and the boundary condition name of any grid point in the grid range corresponding to the element in LISFLOOD-FP is the same as the unique identifier in SWMM; finally, the element flow exchange channel between SWMM and LISFLOOD-FP is established, and a synchronous changing vector-grid flow exchange channel is provided for SWMM and LISFLOOD-FP, the channel stores the flow velocity information of the element to perform flow exchange and distribution.

[0038] Finally, the flow exchange and distribution between SWMM and LISFLOOD-FP are performed: in the consistent time process, the flow exchange and distribution of the same element are performed according to the established spatial matching rule, and the output results and statistical information are obtained.

[0039] Generally, the flow of vertical flow exchange between nodes tends to use weir flow and orifice calculation formula, in a SWMM and LISFLOOD-FP object-oriented coupling method considering the spatial form of elements, the flow exchange needs an additional flow distribution process while calculating the formula. When the SWMM element node overflows, the overflow flow needs to be distributed to each grid point corresponding to the same element in LISFLOOD-FP according to the user-defined rule (such as area average method, etc.); the flow value of the time series of the boundary condition of each corresponding grid of LISFLOOD-FP is:

[0040] q = Q / n

[0041] Where Q is the node overflow flow in SWMM, n is the number of grid points corresponding to the element node, and q is the time series flow rate value of the node.

[0042] When the flow of LISFLOOD-FP element object enters the SWMM pipe network, the flow in the element range of LISFLOOD-FP is included in the calculation, and the flow enters the pipe network according to the user-defined rule (such as area average method, etc.), and the corresponding flow value is subtracted from each grid corresponding to the element in LISFLOOD-FP.

[0043]

[0044] Where the total inflow of the SWMM element is Q, the outflow of each grid corresponding to the element in LISFLOOD-FP is q, n is the number of grid points corresponding to the element node, C is an empirical parameter, A is the area of the inspection well, and h is the water depth of the point.

[0045] Figure 2 An example of setting up a SWMM element and its identifier; Figure 2 A node with a unique identifier A (which can represent a drainage building, pipe point, etc. element in real life) is created, and the time series of A flow is initialized.

[0046] Figure 3 An example of setting up a LISFLOOD-FP element and its identifier; Figure 3 The grid range corresponding to the LISFLOOD-FP element A is created, which consists of n grid points with coordinates (x1, y1), (x2, y2), …, (xn, yn), and their time series are initialized.

[0047] Figure 4The expression and spatial coupling mode of the element object supported by the present application includes the expression and spatial coupling of point-point objects, the expression and spatial coupling of point-point set objects, and the expression and spatial coupling of point-surface objects. The present application can adopt different spatial coupling modes with different degrees of generalization according to the project requirements. When the research project pays more attention to efficiency, the point-point coupling mode can be adopted for urban rain flood simulation; when the research project pays attention to the expression of different scales of elements, the point-surface coupling mode can be adopted; when the research project pays attention to the distribution of the pipe network inside a single drainage building, the point-point set coupling mode can be adopted.

[0048] Figure 5 The simulation effect example of the present application is shown in (b). There are three pipe points in (b) representing three elements in reality. The leftmost pipe point represents the drainage building object, and the two pipe points on the right represent two pipe point objects with lower water depth. The spatial positions of the three pipe points correspond to the three lowest water depths in (a). Since all the three elements have drainage effects, there are three lowest water depths in (a). Since the drainage building occupies a larger area, it represents multiple grid points in the grid, so the drainage building is coupled with the leftmost pipe point in (b) by using the point-surface coupling mode, and thus a surface drainage area appears in (a). Since the two pipe points occupy a small area and only represent one grid point in the grid, the two elements are still coupled by using the point-point coupling mode, and thus two point-shaped drainage areas appear in (a). In addition, if the drainage building is further refined and each pipe in the drainage building is described, the leftmost drainage building in (b) can also be described as multiple grid points at the pipe positions in (a), so as to realize point-point set coupling.

[0049] Compared with the traditional point-point spatial matching method, the present application takes into account the different levels of abstraction of elements in the two-dimensional hydrodynamic model, the expression of elements takes into account the morphological characteristics of elements, and the spatial matching is based on the semantic characteristics of element objects, so as to avoid element mismatch caused by spatial position errors.

[0050] The present application takes into account the morphological characteristics of elements, generalizes drainage elements larger than the grid resolution into grid surface elements to reflect the flow distribution and allocation of large drainage facilities on the grid, and can also establish a point set reflecting the spatial position of the internal pipe points of the elements according to the distribution of the internal pipe points, and construct the spatial coupling relationship between the element objects based on the semantic information of the element objects. Due to the various sizes and spatial scales of the elements in the urban rain flood simulation, and the complex internal pipe network distribution, simply generalizing buildings into points is not enough to accurately describe the discharge of accumulated water on the buildings, and generalizing the elements into element surfaces or point sets of internal pipe points can more accurately describe the flow and discharge of surface accumulated water at the position of the drainage elements. The present application takes into account the differences in spatial expression of elements, supports the expression and flow exchange of vector points and grid points, surfaces, point set element objects, and establishes spatial matching rules for element objects based on the semantic information of the elements, and the matching mode of the element objects is unique.

Claims

1. A method for object-oriented coupling of SWMM and LISFLOOD-FP that takes into account the spatial morphology of elements, characterized in that, Includes the following steps: (1) Determine the elements to be coupled in SWMM and LISFLOOD-FP; the element objects are expressed as nodes in SWMM and have a unique identifier to identify the element, while they exist as raster multipoints in LISFLOOD-FP. (2) Based on the semantic information of elements, a unified spatial matching rule is established between SWMM and LISFLOOD-FP models for different generalized forms of geographic elements in the model; (3) Perform traffic exchange and allocation between SWMM and LISFLOOD-FP: During a consistent time process, perform traffic exchange and allocation for elements with the same name according to the spatial matching rules established in step 2; The coupling elements mentioned in step (1) include three types: point objects, surface objects, and point set objects. When the shape and size of the element are smaller than the grid space resolution, the grid range is points. When the shape and size of the element are larger than the grid space resolution, if the distribution of the pipe network inside the building is not considered, the grid range is surface. Otherwise, the grid range of the element is a point set. The implementation process of step (2) is as follows: (21) Construct the spatial range mapping of elements and determine the vector and raster boundaries of geographic elements; the vector spatial position of a geographic element is the absolute coordinate of the geographic element. For the raster boundary, if the raster element type is a point, the raster boundary is the raster row and column number of the corresponding position; if the raster element type is a polygon, the raster boundary is the raster range row and column number of the corresponding element polygon; if the raster element type is a point set, the raster boundary is the accurate spatial position row and column number of the internal management point of the corresponding element. (22) Construct the semantic mapping relationship between SWMM and LISFLOOD-FP; use QVAR boundary conditions in LISFLOOD-FP, and make the boundary condition name of any grid point within the grid range corresponding to the feature in LISFLOOD-FP the same as the unique identifier in SWMM. (23) Establish an element flow exchange channel between SWMM and LISFLOOD-FP: Provide a synchronously changing flow exchange channel for SWMM and LISFLOOD-FP. The channel stores the flow rate information of elements for flow exchange and allocation.

2. The object-oriented coupling method of SWMM and LISFLOOD-FP considering the spatial morphology of elements according to claim 1, characterized in that, The implementation process of step (3) is as follows: When a feature node overflows, the overflow flow is redistributed across the corresponding surface raster using the flow exchange channel. The flow value for the boundary condition time series on each corresponding raster in LISFLOOD-FP is: q = Q / n Where Q is the node overflow in SWMM, n is the number of raster points corresponding to the feature node, and q is the flow rate value of the node in the time series. When no element node overflows, the element flow of LISFLOOD-FP enters the SWMM network through the flow exchange channel. The flow within the element range in LISFLOOD-FP is included in the calculation, and the corresponding flow value is subtracted from each grid cell corresponding to the element in LISFLOOD-FP. The water on the surface grid cell corresponding to the element is weighted and then flows into the network. Wherein, the total inflow of the SWMM element is Q, the outflow of each grid cell corresponding to the element in LISFLOOD-FP is q, n is the number of grid points corresponding to the element node, C is an empirical parameter, A is the area of ​​the inspection well, and h is the water depth at that point.

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